A variation of the proposed action described in the May 9, 2016, version of Resolution Copper’s General Plan of Operations, this alternative would include a split-stream tailings processing method with two tailings types.

It shares several similarities with Alternative 2, but proposes to reduce the amount of water retained in non-potentially acid generating (NPAG) tailings as well as reduce seepage potential through on-site thickening of NPAG tailings and ‘Thin-lift’ (also known as thin layer) deposition.

The Forest Service held workshops to 1) update the public on the status of the EIS process 2) describe the alternatives development process, and 3) solicit input on the criteria being used to evaluate alternative tailings storage facility locations.